The earliest and most famous of the new styles, emerging in the mid-1960s, is called minimalism. A sharp reaction to the complexities of modernist composition, minimalist music uses very simple melodies, motives, and harmonies repeated many, many times. Terry Riley’s In C, described on page 360, is an ancestor of minimalism (some say the first great example of it). As this example suggests, minimalist composers carried on at least one aspect of modernist experimentation: its presentation of long, slowly changing blocks of musical time.

Minimalism has worked wonders for American opera, which has become the success story of modern music since Einstein on the Beach (1976), by a leading minimalist composer, Philip Glass (b. 1937). Later works such as Satyagraha and Akhnaten, by Glass, and Nixon in China and The Death of Klinghoffer, by John Adams (b. 1947), have been performed again and again in this country and abroad, all of them in spectacular productions.

Steve Reich, a philosophy major at Cornell, studied music subsequently and has become, alongside Glass, an acknowledged old master of the minimalist style. A keyboardist, he has performed his work with his own special group — a practice that a number of other contemporary composers follow. His early music explores issues of rhythm and timing in a rather abstract fashion, experimenting with simple, repeated gestures that gradually shift out of and into phase with one another. This can be achieved in various ways, with one performer gradually changing tempo while another stays constant, for example, or by lengthening certain aspects of the initial pattern while keeping others the same. The most famous of Reich’s early works are Piano Phase (1967), Four Organs (1970), and Clapping Music (1972).

Reich’s later music has broadened from these abstract processes. One of his most impressive pieces, Different Trains (1988), included recorded speech and personal memories, and Reich went on to write operas — The Cave (1998) and Three Tales (2002) — with his wife, video artist Beryl Korot.